1. Field of the Invention
The present invention relates to an optical-fiber lighting unit, preferably intended for use in dental work, and comprising a casing, in which there is provided an optical system to which a plurality of optical-fiber light conductors are optically switchable via a light switch.
2. Description of the Prior Art
The fiber optics technology is utilized in many different branches and includes the transmission of light through long, thin fibers of glass or other transparent materials. The light is conducted through the fibers in a non-electrical manner by being reflected from wall to wall. No heat is transmitted or generated during this process.
In many types of precision mechanical work it is desirable, and often completely necessary, that a large amount of cold light may be supplied to a work area to enable the work to be performed correctly. Not least for dentists, this is a problem. It is difficult to obtain sufficient light in the oral cavity and at the same time perform work on e.g. a tooth. The dentist himself will often cause, with his body, hand or tool, shadowing of the light provided e.g by adjustable lamps and the like. The teeth are in themselves uneven and are located unevenly in relation to each other which for instance causes that parts of the teeth will be shadowed. Furthermore, it is difficult to get sufficient light for example into bores and at the innerside of the rows of teeth.
Various optical-fiber lighting units are presently commercially available, for example for use in diagnostics but above all for use in dental work. These units are usually made with a space-consuming and heavy apparatus unit in which there are provided a transformer, a fan and a light bulb with a concave mirror. One or several optical-fiber light conductors are connected by means of a coupling to the apparatus unit and are from there extended to one or several hand-held instruments such as hand-mirrors, dental turbines or the like, to which the fiber-optics is connected by means of e.g clips. Mostly, it is necessary to have several light conductors which can be mounted more or less permanently on some of the most frequently used dental tools, as for example a high speed turbine, a low speed electrical motor and a probe. Due to the unwieldy design the unit must be placed comparatively far away from the place of work, so that consequently also the optical-fiber light conductors have to be made long, for instance 2-3 meters. Due to the light losses in the optical-fiber light conductor, which losses may attain a value of 50% per meter, the light bulb used in the unit must admit light of a high intensity and must therefore be a high-power lamp, which at the same time results in the lamp giving off much heat. As an example, in a commercially available unit the light bulb has a power of 150 W. One disadvantage of using such light bulbs are that they are short lived-the manufacture of the optical-fiber lighting unit in question estimates the burning time to be 80-100 hours. Another disadvantage is that the high emission of heat from the unit will inconvenience the dentist as well as the patient. Furthermore, a comparatively large fan must be used for cooling the unit and this fan introduces disturbing noise into the work environment.
In the case where several optical-fiber light conductors, e.g. three, are connected to the same unit, all of them are activated, i.e they give up light, even those that are not used for the time being. Usually the dentist only needs to use one fiber light conductor at the time, e.g. the one mounted on the turbine or the one mounted on a probe, which means that the unit generates unnecessarily much light and heat, since the light bulb of the unit has to be dimensioned so that the light power is sufficient for all three light conductors at the same time.